1. Field of the Invention
The present invention relates to an apparatus for automatically weighing a number of different kind of powder materials in accordance with a desired mixing ratio.
Recently there has occurred a necessity for automatically and accurately weighing powder in the order of milli-gram for the purpose of production of a new mixture by mixing inorganic materials such as ceramics, cement or the like.
2. Related Art Statement
Hitherto, such an apparatus for accurately weighing powder material comprising a vibrating feeder provided at an outlet of a hopper for automatically feeding a powder material into a weighing cup mounted on an electronic balance has been known.
Such a known weighing apparatus is however adapted for weighing only one kind of powder material. Accordingly, in case of weighing other kinds of powder material, it is necessary that the powder hopper is interchanged with other powder hoppers and the vibrating feeder is also interchanged or washed so as not to be mixed or contaminated by the powder material which has been previously weighed. Such an operation requires extensive labor and time loss. Furthermore, there are problems such that it is difficult to prevent perfectly the previously weighed powder material from mixing into the next weighing powder material and the accuracy of weighing is not satisfied. Therefore, the known apparatus can not be utilized for weighing a powder material used, for example in a paint or a medicine which must not be permitted to be mixed or contaminated with other powder materials.